US 6857493 B2
A system for adjusting the position of a load supported on a conveyor cart includes a driven lift mechanism for controlling height and a turntable for controlling rotational orientation. The cart may, alternately or in addition to the above mechanisms, include a gimbal mechanism for rotational adjustment about multiple axes. A processor on the cart provides actuation and control of the mechanisms. An ID card reader on the cart senses ID tags for determining when the cart is adjacent particular locations. Data representing desired load position at the locations is stored either in a memory device or by the ID tag for relay to the processor on the cart via the ID tag reader. A system level controller provides a centralized storage location for desired load position data for communication to a plurality of conveyor carts through a communication link that includes radio frequency modems.
1. A conveyor system comprising:
at least one conveyor cart having a platform for supporting a load and a base, the cart adapted to be conveyed along a path within a facility;
at least one driven adjustment mechanism for adjusting the position of the supported load with respect to the base;
a control processor located on-board the cart for actuating and controlling the at least one position adjusting mechanism;
means for determining proximity of the cart to at least one location within the facility; and
means for storing data representing desired load position adjustment for each of the locations within the facility, the controller actuating and controlling the adjustment mechanism according to the position data stored for a particular location when proximity of the cart to the location is determined.
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13. A control system for adjusting a load supported on a conveyor cart platform, the system comprising:
a driven lift mechanism connected to the conveyor cart platform for adjusting the height of the platform;
a driven rotational adjustment mechanism supported by the platform for adjusting the rotational orientation of a load supported on the platform; and
an on-board processor operably connected to each of the mechanisms for actuation and control of the mechanisms by the processor.
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15. The control system according to
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18. A method of adjusting a load carried by a conveyor cart capable of being directed along a path adjacent at least one location in a facility, the method comprising the steps of:
providing at least one driven mechanism for adjusting the position the load with respect to the cart;
providing a sensor capable of determining proximity of the cart to the at least one location;
providing a control processor connected to the adjustment mechanism for actuating and controlling the mechanism;
directing the conveyor cart along the path;
determining where the cart is relative to the at least one location;
actuating the adjusting mechanism when the cart is at a specific location with respect to the at least one location.
19. The method according the
20. The method according to
providing a system level controller capable of storing data representing desired load position for the locations;
providing a communications means linking the system level controller to the control processor of the conveyor cart;
notifying the system level controller via the communication link when the sensor determines that the cart is adjacent the at least one location;
retrieving the desired load position for the sensed location stored by the system level controller; and
relaying the desired load position for the sensed location to the control processor of the conveyor cart via the communication link.
21. A cart for a conveyor system comprising:
a base having a plurality of wheels;
a scissors lift mechanism mounted on the base and the platform, the lift adapted to adjust the height of the platform relative to the base;
a sensor mounted on the cart for sensing a signal indicative of the location of the cart; and
a controller mounted to cart, the controller in communication with the sensor for receiving sensed signals indicative of the location of the cart, the controller also in communication with the scissors lift mechanism for controlling actuation of the mechanism, the controller actuating the scissors lift mechanism for adjusting the height of the platform to a prescribed height based on the location of the cart.
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This application is related to and claims priority from provisional application Ser. No. 60/356,550, filed Feb. 13, 2002, which is incorporated herein by reference in its entirety.
The present invention relates to conveyor systems and more particularly to a system for controlling the height and rotational/angular orientation of a load carried by a conveyor cart.
In assembly line manufacture, workpieces are conveyed along a path between multiple stations where operators perform sequential tasks on the workpieces. The workpieces are commonly supported on wheeled carts conveyed along the path by a drive system to which the cart is secured.
It is desirable to provide adjustability in the height at which the workpieces are supported by the carts. Adjustment in the height of a supported workpiece facilitates the performance of differing tasks on the workpiece. Such adjustment also facilitates the performance of a task by differing operators by providing for adjustments based on operator height or individual preferences, for example. It is known to include motor driven scissors-lift mechanisms for adjustment in the height of a load supporting platform. In U.S. Pat. No. 6,112,858 to Arnst (incorporated herein by reference in its entirety), actuation and control of the scissors-lift mechanism is limited to simple on-off control provided by foot-peddles carried by the base portion of the cart.
It is also desirable to provide for adjustability in the rotational orientation of a cart supported workpiece. Such adjustment in the rotational orientation facilitates the performance of tasks on opposite sides of the workpiece or for providing additional access to the workpiece, for example. In Arnst '858, a pivotably supported turntable provides for adjustment of the rotational orientation of a supported load. The adjustment in the orientation of the workpiece, however, is limited to rotational adjustment about a vertical axis (i.e., about a single axis). Also, the turntable disclosed in Arnst '858 is not motor driven. Adjustment of the rotational orientation of a supported load in Arnst, therefore, requires that the workpiece be rotated manually by an operator at a particular station on the assembly line.
According to the present invention, there is provided a system for adjusting the position of a load supported on a platform of a conveyor cart. The system includes a driven lift mechanism connected to the platform for adjusting height. The lift mechanism is most preferably a hydraulically or pneumatically driven scissors mechanism.
The system also preferably includes a driven mechanism, most preferably a turntable, for adjusting rotational orientation. Alternatively, the system could include a gimbal mechanism or multi-axis positioning system for rotational and angular adjustment about multiple axes.
The system also includes an on-board controller mounted on the cart for controlling the operation of the load position adjusting mechanisms.
According to one embodiment of the invention, the system includes sensing means carried by the cart for determining proximity of the cart to station locations along a path of the cart. The means for sensing most preferably includes an RF tag reader mounted on the cart for sensing programmable RF tags mounted adjacent to station locations. Desired load position information may be stored on the RF tag for transmission to the RF tag reader. Alternately, the cart processor may include a memory device for storage of load position data for each of the locations.
According to another embodiment of the invention, the system includes a system-level controller for central storage of load position data for each station location A communication system provides for transmission of the position data from the system level controller to the cart processors. Preferably, the communication system includes a first radio frequency modem or transmission device connected to the system level controller and a second radio frequency modem or transmission device connected to the processor of each cart
For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
Referring to the drawings, wherein like reference numerals illustrate corresponding or similar elements throughout the several views, a system for controlling the height and the angular orientation of a load carried by a conveyor cart is disclosed. Control of load position may be desirable on an assembly line, for example, for raising and lowering of an assembly workpiece for ergonomic reasons or for angular adjustment of the assembly workpiece to allow enhanced operator access or to provide interface with other tools or manipulators.
Referring to the drawings where like numerals refer to like elements, there is shown in
The first arms 20 are pivotably connected to the second arms 22 preferably at a central location (indicated by the numeral 24 in FIG. 1). An end 26 of each of the first arms 20 is pivotably connected to the platform 14 preferably adjacent an end of the platform. An opposite end 28 is secured to a roller or slide 30 received in a track 32 carried by base 16 such that end 28 is slidable with respect to the base 16. An end 34 of each of the second arms 22 is pivotably connected to the base 16. An opposite end 36 is secured to a roller or slide 38 received in a track 40 carried by platform 14 such that end 36 is slidable with respect to the platform 14. The slidable connection of the first and second arms 20, 22, to the base 16 and the platform 14 allows for extension and contraction of the arms and a corresponding change in the height of the platform 14. Alternately, the upper or lower ends of both arms 20, 22 can be pinned to the platform 14 and base 16, respectively. However, in this alternate embodiment, the two arms 20, 22 cannot be pinned to one another (such as at 24) but must be free to move relative to one another.
The scissors lift mechanism 18 includes a motor drive unit 42, preferably of an electro-hydraulic type, having a base portion 44 and a slidably driven rod portion 46 for powered extension and contraction of the first and second arms 20, 22. The lift mechanism 18 includes a crossbeam 48 extending between, and secured at its ends to, the first arms 20. Similarly, a crossbeam 50 is secured at its ends to the second arms 22. The base portion 44 and rod portion 46 of the motor drive unit 42 are pivotably connected to crossbeams 50, 48, respectively such that extension of the rod portion 46 results in extension of the scissors arms 20, 22.
The conveyor cart 10 also includes a motor driven turntable 52 supported by the platform 14 of cart 10. The turntable 52 provides for adjustment in the rotational orientation of a supported load about a vertical axis. A battery 54 carried by the base 16 of the cart 10 provides an on-board power source for the motor driven turntable 52 and for the scissors lift mechanism 18.
The cart 10 includes wheels 56 connected to the base 16 to provide for translation of the cart 10. The cart 10 may be connectable to a chain drive (not shown) of an assembly line conveyor system in the manner well known in the art.
The present invention is not limited to height adjustment using a scissors lift mechanism. Referring to
The present invention is also not limited to the use of a turntable for providing rotational adjustment of a supported load. As shown in
A cart according to the present invention could include other mechanisms, such as a multi-axis positioning system, for providing adjustment in the rotational/angular orientation of a load supported by the cart. A multi-axis positioning system provides for adjustment in the angular orientation of a supported load about a plurality of axes.
Referring again to
As an alternative to on-board operator controls, the control system could include operator controls mounted adjacent to the stations in the facility. The operator's inputs to the station mounted controls could be conveyed to the cart through various means, including RF or IR signals, hardwired plug-ins, etc.
Alternatively, information regarding multiple selectable positions for the load could be stored in memory by the processor 90 for selection by an operator from among multiple preset positions, using buttons numbered 1 through 5, for example. As an alternative to selection of presets using a numbered keypad, the control system 88 could include a multi-position switch connected to the processor 90 for selection among multiple positions stored in the processor. Control over the lift mechanism 82 and turntable 84 by the on-board processor 90, rather than by manual operator control, facilitates achievement of final height and rotational position quickly and smoothly while avoiding mechanical interferences.
The cart 80 of
The control system 88 for cart 80 of
The control system 88 of cart 80 includes an ID tag reader 94 mounted on the cart 80. The ID tag reader 94 is capable of sensing and receiving information from an ID tag, such as tags 96, 98 located adjacent to stations 100, 102 for example. The ID tags may be can be selected from a variety of identification devices, including bar codes or magnetic strips. Although various forms of communication would be suitable for use in the control system 88, it is preferable that radio frequency be used for relaying information from the ID tags 96, 98 to the ID tag reader 94 mounted on the cart 80. The cart 80 is directed along a particular pathway within the facility, for example, to the right in
Alternatively, the cart 80 could include a separate on-board drive system and could be guided through the facility on a rail or track system, or by an imbedded wire in an inductive guidance system known in the art. When the cart 80 approaches one of the stations, such as station 102 as shown in
As an alternative to locating ID tags adjacent the station locations, a removable ID card could be used. The ID card could be preprogrammed with either load position information or a station identifier. The operator would bring the ID card to the station and mount it in a particular location which can be sensed by the ID reader on the cart as the cart approaches the station. Alternatively, an operator could present the ID card to the ID reader as the cart approaches the operator's station. The ID cards may either be specific to an operator or generic to the station. If they are specific to an operator, the ID card may include information about the operator to provide operator specific adjustment. For example, the ID card may include the operator's height and/or whether she is right-handed or left-handed.
The processor 110 of control system 104 includes a memory device 114. The memory device 114 of processor 110 provides for on-board storage of position information for a plurality of stations within a facility for example. In this embodiment, the ID tags at the various stations do not have position information programmed into them as was the case for the ID tags 96, 98 of FIG. 3. Instead, the ID tags need only provide a signal that uniquely identifies a given station such that the processor can distinguish a particular station from the other stations within the facility. This identifying signal is relayed from the ID tag reader 112 to the processor 110. Upon receipt of an identifying signal, the processor 110 accesses the on-board memory storage device 114 to retrieve the position information stored in the memory device 114 for the identified station. Position data for the stations could be added or updated in the memory device 114 by various methods, including telecommunication, electrical interface, etc. For example, during recharging of the on-board batteries, a download of position data can be provided into the memory.
The system level controller 126 is connected to a radio frequency modem or other transmission device 128 that provides a communication link with each of the individual carts within a facility. Each of the separate carts includes a radio frequency modem or other transmission device 130 connected to the processor 122 for receiving information from (and transmitting information to) the system level controller 126. In this embodiment, the system level controller 126 serves as a communications hub in a communication network.
The central location of the system-level controller 126 in the communication network provides for system-level control of load positioning for each of the carts in the following manner. Each of the ID tags for the stations is programmed to transmit only a location identifier (e.g., a station number) in a similar manner to the ID tags in the control system 104 of FIG. 4. When the ID tag reader 124 senses an ID tag, the reader 124 transmits the station identifier to the on-board processor 122. The processor 122 then broadcasts the station identifier to the system-level controller 126 via the communication link provided by RF modems 128, 130. Load position information for the station sensed by the ID tag reader 124 is retrieved from storage by the system-level controller 126 and transmitted back to the on-board processor 122 via modems 128, 130. The processor 122 uses the received information to actuate and control the lift mechanism 118 and turntable 120 in a similar manner to that described previously.
The height and rotational/angular orientation information for each station location within the facility is entered into storage of the system level controller 126 of control system 116 using an operator interface. The control system 116 may be further adapted to interface with a product tracking management system to provide an additional level of control over load position by the control system 116. In this manner, multiple load positions associated with a particular station location may be stored for selection depending on the particular load being conveyed. This may be useful, for example, in applications involving products that are custom assembled according to a buyer's specifications. Depending on the work options available at each station location, the product may need to be presented to a station's operator differently (or stations may be skipped entirely). For example, a station may require one side of the product to be worked on first, then upon completion, the table rotated so that another side can be worked on. The operator may enter a “done” command which is transmitted to the system level computer signaling a change in the position to the next stored value. This additional level of control permits dynamic changes to the load position instructions so that a cart's instruction can be varied according to the specifics of the load carried as well as the requirements of each station. It should be readily apparent that this last feature of the invention is also applicable to the prior embodiment where the position data is stored on the cart.
It is also contemplated that a “learning” function can be incorporated into the embodiment shown in
The inclusion of the system level controller 126 in the control system 116 also provides the additional benefit of allowing an operator at a station to identify a problem with a particular workpiece. The operator could key in a command, for example, for transmission to the system level controller to inform the controller of a problem with the workpiece at the operator's station. The system-level controller could then track the workpiece for subsequent attention. Alternately, the conveyor system could be configured to provide for redirection of the cart, to a repair station off the main assembly line for example, by the system level controller. Referring to
In a similar fashion as the control system 88 of
In each of the automatic control systems shown in
A GPS monitoring system could also be incorporated into the control system 104 of
The system determines the preselected position information either by accessing data stored in memory on-board the cart for use by the control processor of the cart. Alternately, the system determines preselected position information by accessing data stored in memory associated with a central system-level controller using the communication link shown in
While the positioning of the workpiece has been described above as occurring adjacent a work station, it is also contemplated, and in certain situations may be more preferable, that the load position adjustment occur at a distance from the stations. For example, if the workpiece is very large and it needs to be rotated before work can be performed at the next station, obstacles at the station may prevent its rotation. Also, rotating the workpiece near workers can be dangerous. In such situations, an ID Tag can be located in between stations allowing the cart to reposition the workpiece before it reaches the next station. Alternately, repositioning can begin immediately upon the cart sensing that it is leaving a station.
It is also contemplated that an RF communication signal from a central location can be used to update position data stored onboard the cart.
Although the control system of the present invention has been described in conjunction with conveyor carts of a towline type conveyor system, the present invention is not so limited. It is contemplated, for example, that each of the carts could include an independent drive system and that the cart could be preprogrammed to follow a particular assembly line path. Use of an on-board GPS system would facilitate the movement of the cart between stations.
While the present invention has been described in connection with the preferred embodiments of the various figures, it is to be understood that other similar embodiments may be used or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather should be construed in breadth and scope in accordance with the recitation of the appended claims.